You can already do this, but you need every video in its own folder, and then you need to rename your cover jpg to folder.jpg and put it in the same folder as the video, then rescan your media content, and wala you should have coverart for your movie.

See now, my problem is, I have about 100 movies on mine, I don't mind having them all in there own folders, but it is getting a little cumbersome to search through the movies in the All Titles list - still trying to get a good sorting going.